#include<iostream>
#include<stdio.h>
#include<string>
#include<cstring>

using namespace std;

//get user name 
string GetUserName()
{
  string Name = getenv("USER");
  return Name.empty()?"None":Name;
}
//get host name 
string GetHostName()
{
  string HostName=getenv("HOST");
  return HostName.empty()?"None":HostName;
}
//get pwd 
string GetPwd()
{
  string Pwd = getenv("PWD");
  return Pwd.empty()?"None":Pwd;
}

string MakeommandLine()
{
  char *
}

//print command line 
void PrintCommandLine()
{
  printf("%s",MakeommandLine().c_str());

  //need refresh screen 
  fflush(stdout);
}


int main()
{
  //command line must be keep running 
  while(true)
  {
    PrintCommandLine();   //print command line 

    GetCommandLine();     //get command line 

    ParceCommandLine();   //parce command line 

    ExecuteCommandLine(); //execute command line 
  }
  return 0;
}
